(FORTUNE Small Business) -- When President Bush announced his April nomination of Steven Preston to replace Hector Barreto at the Small Business Administration, the response could have been summed up in one word: Who? Preston--who left his post as executive vice president at ServiceMaster, a $3.2-billion-a-year Chicago landscape and home-maintenance company (servicemaster.com), to pursue the nomination--has spent his career working for large companies. He is a virtual unknown in Washington, with seemingly little clout. Ken Hooten, managing partner of Concentric Equity Partners, a Chicago investment fund on whose advisory board Preston serves, says he never knew that Preston wanted to run the SBA. "I don't think he has political aspirations," says Hooten. "He just wants to make a difference."

A Sunday-school-teaching father of five, Preston, 45, likely came to Bush's attention through Claire Buchan, a former ServiceMaster vice president of communications who has served as deputy assistant to President Bush. (ServiceMaster's first corporate objective--"To honor God in all that we do"--probably did not hurt Preston's chances.) Preston is a small-government, laissez-faire conservative whose ideologies were shaped by the education he received at the University of Chicago in the mid-1980s, says Dan Kenary, a former classmate from that school's MBA program. Kenary adds that Preston nonetheless supports the SBA's loan programs, seeing them as a "pretty efficient way to create jobs." But not everyone is convinced; Lloyd Chapman, president of the American Small Business League (asbl.com), says that during Preston's tenure, ServiceMaster lobbied Congress to limit the amount of federal small-business contracts, and refers to the company as "anti-small business." (Preston declined an interview, pending the confirmation process.)

Preston's supporters shrug off his lack of small-business experience, pointing to his years at ServiceMaster--where he approved loans to franchisees--and at investment banks and funds. Karen Kerrigan, head of the conservative Small Business & Entrepreneurship Council (sbsc.org), says that while she supports Preston, she worries whether he will be "in tune" with entrepreneurs' needs: "Not all small business are turnkey franchises."